bossraid
A term that seemingly originated from the ROBLOX permadeath game Rogue Lineage, defining a player who can take on a large number of other players alone. Can be used as a verb, or an adjective. Possibly the player version of "raidboss"
*A player playing the oni class kills 3 other guys while outnumbered 5 to 1*
Player 1: "Holy shit, that dude is bossraiding so hard right now!" (Verb)
Player 2: "What a bossraid oni!" (Adjective)
Player 1: "Holy shit, that dude is bossraiding so hard right now!" (Verb)
Player 2: "What a bossraid oni!" (Adjective)